Power supply unit, generator, and wind turbine generator

ABSTRACT

A power supply unit of the invention comprises a battery  4  that stores electric power used for operations of various devices; a dynamo  19 , a rotation support mechanism  14 , and a rectifying section  32  as charging means that converts natural energy into electric energy and supplies electric power of the electric energy to the battery  4  to be charged; a charging control section  36  for changing over between supply and stop of the electric power from the charging means to the storage means; and a charging control driving unit  45  and a low-voltage charging function of an arithmetic processing part  51  as charging changeover control means that controls the charging control section  36  such that supply and stop of the electric power are repeated when the charging voltage for charging the battery  4  with electric power is not less than a predetermined value, and continues supply of the electric power when the charging voltage is less than the predetermined value.

TECHNICAL FIELD

The present invention relates to a power supply unit, a generator, and awind turbine generator for converting natural energy such as wind energyinto electric energy to be used as electric power for various devices.

BACKGROUND ART

JP-A-2003-284393, JP-A-2003-21046, JP-A-2003-327678, andJP-A-2003-278637 disclose generators for generating electric power usingnatural energy such as wind power. In such a generator, a rotating shaftto be rotated by wind power is connected to a dynamo to convert kineticenergy into electric power of electric energy. The generator includestherein a power supply unit in which a battery is charged with theelectric power as power supply for various devices such as electriclights. Thereby, the generator can stably supply electric powerirrespective of presence/absence of wind or a change in wind.

However, charging is performed with a high charging voltage upon astrong wind for example, while charging is performed with a low chargingvoltage upon a weak wind. Thus, the battery is charged with the chargingvoltage that may change widely. There is a problem that such aconventional generator is low in charging efficiency.

In addition, natural energy is very unstable energy. If electric poweris continuously supplied to an external load while no electric power issupplied from the generator for a long time or when the electric powerthat can be obtained from natural energy is insufficient in itself forthe external load, the battery may be over discharged. This causes aproblem of shortening the life of the battery.

Further, in case that a state of windlessness continues for a long time,even while power supply to external devices is stopped, the discharge ofthe battery goes on and the charging voltage is extremely lowered. Thiscauses a problem of bringing about a trouble in which an externalcontroller erroneously operates or can not operate because of electricpower of a too low voltage.

Further, in case that the rotating shaft to be rotated by wind power isconnected to the dynamo for electric power generation, the rotatingshaft must bear the load for operating the dynamo. In this case, whenthe wind power is weak in comparison with the load, the wind turbine maystop. This causes a problem of making sufficient generation impossible.

Further, if the maximum electric current is always supplied continuouslyfrom the start of an operation of an electromagnetic clutch, which isprovided for idling the wind turbine upon a breeze, to the end of theoperation of the clutch, the consumption of the supplied current islarge. This causes a problem of decreasing the gain to the electricpower obtained from the dynamo.

Therefore, a first object of the present invention is to make itpossible to efficiently charge the battery even in case that thecharging voltage changes widely because of a change in wind power.

A second object of the present invention is to prevent storage meansfrom being over discharged even in case of unstable electric powersupplied from generating means, and to protect thereby the storagemeans.

A third object of the present invention is to keep the battery in thecharging voltage of a predetermined value or more even in case that astate of windlessness continues for a long time.

A fifth object of the present invention is to make it possible torealize sufficient generation of electric power even in case of smallnatural energy.

A fifth object of the present invention is to make it possible torealize effective generation of electric power.

DISCLOSURE OF THE INVENTION

A power supply unit of the present invention comprises a storage meansfor storing electric power that is used for operations of variousdevices; a charging means for transforming natural energy into anelectrical energy, and charging by supplying an electric power as theelectric energy to the storage means; a charging changeover means forchanging over between supply and stop of the electric power from thecharging means to the storage means; and a charging changeover controlmeans for controlling the charging changeover means such that supply andstop of the electric power are repeated when a charging voltage forcharging the storage means with electric power is not less than apredetermined value, and continues supply of the electric power when thecharging voltage is less than the predetermined value.

According to this feature, when the charging voltage to the storagemeans is not less than the predetermined value because of large naturalenergy, supply and stop of electric power to the storage means arerepeated and thereby the storage means is charged with charging currentbeing throttled under a high charging voltage. On the other hand, whenthe charging voltage to the storage means is less than the predeterminedvalue because of small natural energy, by continuing supply of electricpower to the storage means, the storage means is charged with chargingcurrent as large as possible under a low charging voltage. Therefore,even in case that the charging voltage may change widely due toincrease/decrease of the natural energy, the storage means can beefficiently charged.

In addition, a power supply unit of the present invention comprises astorage means for storing electric power that is used for operations ofvarious devices; a charging means for transforming natural energy intoan electrical energy, and charging by supplying an electric power as theelectric energy to the storage means; a charging changeover means forchanging over between supply and stop of the electric power from thecharging means to the storage means; and a charging changeover controlmeans for controlling the charging changeover means such that supply andstop of the electric power is changed over at stop time intervalscorresponding to a charging voltage for charging the storage means withelectric power.

According to this feature, when the charging voltage for charging thestorage means is raised because of large natural energy, the supply timeis shortened because of an increase in stop time interval. Thus, thestorage means is charged with charging current being throttled. On theother hand, when the charging voltage for charging the storage means islowered because of small natural energy, the supply time is elongatedbecause of a decrease in stop time interval. Thus, the storage means ischarged with charging current as large as possible under a low chargingvoltage. Therefore, even in case that the charging voltage may changewidely due to increase/decrease of the natural energy, the storage meanscan be efficiently charged.

In addition, a power supply unit of the present invention comprises astorage means for storing electric power that is used for operations ofvarious devices; a charging means for transforming natural energy intoan electrical energy, and charging by supplying an electric power as theelectric energy to the storage means; a charging changeover means forchanging over between supply and stop of the electric power from thecharging means to the storage means; and a charging changeover controlmeans for controlling the charging changeover means such that supply andstop of the electric power are repeated at stop time intervalscorresponding to a charging voltage for charging the storage means withelectric power when the charging voltage is not less than apredetermined value, and continues supply of the electric power when thecharging voltage is less than the predetermined value.

According to this feature, when the charging voltage for charging thestorage means is not less than the predetermined value, supply and stopof electric power to the storage means are repeated and thereby thestorage means is charged with charging current being throttled under ahigh charging voltage. On the other hand, when the charging voltage forcharging the storage means is less than the predetermined value, bycontinuing supply of electric power to the storage means, the storagemeans is charged with charging current as large as possible under a lowcharging voltage.

In addition, a generator of the present invention comprises an electricpower generation means for generating electric power; a storage meansfor storing electric power generated by the electric power generationmeans; an output means for outputting electric power stored in thestorage means to an external load or stopping the output; a voltagedetection means for detecting a voltage of the electric power generatedby the electric power generation means; and a control means forcontrolling the output means. The control means stops the output ofelectric power to the external load when the voltage detected by thevoltage detection means is not more than a predetermined value.

According to this feature, because the output of the electric power isstopped when the voltage of the electric power generated by the electricpower generation means is insufficient, the storage means can beprevented from being over discharged. Thus, the storage means can beprotected.

In addition, a power supply unit of the present invention comprises astorage means for storing electric power that is used for operations ofvarious devices; a charging means for transforming natural energy intoan electrical energy, and charging the storage means with the electricenergy; an auxiliary charging means for charging the storage means withauxiliary electric power; and a charging control means for monitoringthe charging voltage of the storage means and permitting that theauxiliary charging means charge auxiliary electric power to the storagemeans when the charging voltage is less than a predetermined value.

According to this feature, because the auxiliary charging means chargesthe storage means with auxiliary electric power when the chargingvoltage of the storage means has lowered to less than the predeterminedvalue, the charging voltage of the storage means is always kept to thecharging voltage of not less than the predetermined value. Thereby, atrouble can be prevented in which various devices erroneously operate orcan not operate due to electric power of a too low voltage. In addition,the storage means can be prevented from being over discharged.

In addition, a power supply unit of the present invention comprises astorage means for storing electric power that is used for operations ofvarious devices; a charging means for transforming natural energy intoan electrical energy, and charging the storage means with the electricenergy; and an auxiliary charging means for charging the storage meanswith auxiliary electric power such that the storage means has a chargingvoltage of not less than a predetermined value.

According to this feature, because the auxiliary charging means chargesthe storage means with auxiliary electric power when the chargingvoltage of the storage means has lowered to less than the predeterminedvalue, the charging voltage of the storage means is always kept to thecharging voltage of not less than the predetermined value. Thereby, atrouble can be prevented in which various devices erroneously operate orcan not operate due to electric power of a too low voltage. In addition,the storage means can be prevented from being over discharged. Further,the storage means can be charged with the auxiliary electric power usinga small number of parts.

In addition, a power supply unit of the present invention comprises adriving force generation means for generating driving force byconverting natural energy into kinetic energy; a measurement means formeasuring the magnitude of the driving force; an electric powergeneration means for generating electric power by being operated withthe driving force of the driving force generation means; a changeovermeans for changing over between transmission and interruption of thedriving force of the driving force generation means to the electricpower generation means; and a changeover control means for controllingthe changeover means such that the driving force from the driving forcegeneration means to the electric power generation means is interruptedwhen the magnitude of the driving force measured by the measurementmeans is less than a predetermined value, and the driving force istransmitted from the driving force generation means to the electricpower generation means when the magnitude of the driving force is notless than the predetermined value.

According to this feature, even in case of a small driving force, thatis, even under conditions of small natural energy, by alternatelyrepeating transmission and interruption of the driving force to theelectric power generation means by the changeover control means, thegeneration efficiency of the electric power generation means can beimproved. In case of small natural energy, the driving force is weak. Inaddition, some load may be applied to the driving force generation meanswhen the driving force is transmitted to the electric power generationmeans. Therefore, when the driving force is weak in comparison with theload, there is a fear that the driving force generation means isstopped.

Such load can be eliminated by interrupting the transmission of thedriving force to the electric power generation means when the drivingforce is less than the predetermined value. Thus, the driving forcegeneration means can continue to operate without stopping. By using theforce of inertia at this time, even when the driving force istransmitted to the electric power generation means, the driving forcegeneration means does not stop. When the driving force has again loweredto less than the predetermined value, the transmission of the drivingforce to the electric power generation means is interrupted. Thereby,the driving force generation means continues to operate withoutstopping. By this manner, even in case of small natural energy, thedriving force can be increased as much as possible and sufficientelectric power generation can be realized.

In addition, a power supply unit of the present invention comprises adriving force generation means for generating driving force byconverting natural energy into kinetic energy; an electric powergeneration means for generating electric power by being operated withthe driving force; an energisation operation type clutch means forchanging over with clutch force corresponding to operation currentbetween transmission and interruption of the driving force from thedriving force generation means to the electric power generation means;and a clutch control means for outputting the operation current to theclutch means with controlling the operation current such that the clutchforce is increased in accordance with the driving force.

According to this feature, because the operation current to be suppliedto the clutch means is controlled in accordance with the driving force,the consumption of the operation current can be decreased. In comparisonwith a case wherein a certain operation current continues to be suppliedto the clutch means, the ratio of the electric power obtained bygeneration to the operation current used in the generation is improved.This realizes effective electric power generation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a wind turbine generator according to afirst embodiment of the present invention.

FIG. 2 is a diagram for explaining the whole construction of the windturbine generator of FIG. 1.

FIG. 3 is a block diagram of an auxiliary charger.

FIG. 4 is an external view of an operation display unit 3 illustrated inFIG. 1.

FIG. 5 is a flowchart of a rotating shaft clutch operation.

FIG. 6 shows graphs for explaining a state of charging a battery.

FIG. 7 is a flowchart of an operation procedure of a battery protectionfunction by a control part illustrated in FIG. 1.

FIG. 8 is a block diagram of the auxiliary charger.

FIG. 9 is a chart for explaining a state of auxiliary charging.

FIG. 10 is a graph showing changes in the rotational speed of a rotationsupport mechanism and in the voltage generated by the wind turbinegenerator.

FIG. 11 is a diagram of the whole construction of a wind turbinegenerator according to a second embodiment of the present invention.

FIG. 12(a) is a graph showing a relation between the rotational speed ofa wind turbine and the rotation driving force. FIG. 12(b) is a chartshowing a conventional timing for supplying a clutch operation currentto the rotating shaft clutch, relative to the rotational speed of thewind turbine shown in FIG. 12(a). FIG. 12(c) is a chart showing aconventional timing for supplying a clutch operation current to therotating shaft clutch, relative to the rotational speed of the windturbine shown in FIG. 12(a). FIG. 12(d) is a chart showing a timing forsupplying a clutch operation current to the rotating shaft clutch,according to a preferred embodiment, relative to the rotational speed ofthe wind turbine shown in FIG. 12(a). FIG. 12(e) shows a modification ofFIG. 12(d).

FIG. 13 is a flowchart of an operation in relation to the rotating shaftclutch.

BEST FORM FOR CARRYING OUT THE INVENTION First Embodiment

Hereinafter, a first embodiment of the present invention will bedescribed with reference to FIGS. 1 to 10.

As illustrated in FIG. 1, a power supply unit according to thisembodiment is installed in a wind turbine generator. The wind turbinegenerator includes a wind turbine generator main body 1 for convertingwind energy as a kind of natural energy into alternating electric powerof electric energy to be output; a controller 2 having a function ofcontrolling the wind turbine generator main body 1, a function ofrectifying alternating electric power into direct electric power, etc.;an operation display unit 3 for displaying the operating condition,setting condition, etc., of the wind turbine generator; a battery 4(storage means) to be charged with the direct electric power rectifiedby the controller 2; an inverter 5 (output means) for converting theelectric power stored in the battery 4 into alternating electric powerto be supplied to an external load 6; and an auxiliary charger 7 forsupplying auxiliary electric power to the battery 4.

As illustrated in FIG. 2, the above wind turbine generator main body 1includes a wind turbine 11 (driving force generation means) forgenerating rotation driving force in accordance with wind power. Thewind turbine 11 includes wind turbine blades 12 (rotation bodies) forreceiving wind, a gyration support member 13 supporting the wind turbineblades 12 such that they can gyrate horizontally, and a rotation supportmechanism 14 supporting the rotational center of the gyration supportmember 13. The rotation support mechanism 14 stands vertically. Therotation support mechanism 14 includes a first rotating shaft member 15(rotating shaft) connected at its upper end to the rotational center ofthe gyration support member 13, and a second rotating shaft member 17connected to the first rotating shaft member 15 through a rotating shaftclutch 16 (changeover means).

The above first rotating shaft member 15 is provided with a rotationalspeed detector 18 (measurement means/voltage detection means). Therotational speed detector 18 comprises an encoder, which outputs arotational speed signal of the number of pulses in accordance with therotational speed of the first rotating shaft member 15 (the number ofrevolutions per unit time). Alternatively, the rotational speed detector18 may have a construction in which a detection object such as a magnetor a reflection plate is attached to a side face of the gyration supportmember 13 such that a rotational speed signal pulse is output every timewhen the detection object is detected.

The rotating shaft clutch 16 interposed between the rotating shaftmembers 15 and 17 is constructed into a deenergization operation type.More specifically, the rotating shaft clutch 16 includes two clutchplates 16 a, a non-illustrated spring member for biasing the clutchplates 16 a to be joined to each other, and a coil member 16 b forgenerating electromagnetic force in the opposite direction to thebiasing force of the spring member. Thus, when no clutch operationcurrent is supplied, the clutch plates 16 a are strongly joined(coupled) to each other by the biasing force of the spring tosufficiently transmit the rotation driving force of the first rotatingshaft member 15 to the second rotating shaft member 17. When a clutchoperation current is supplied, the electromagnetic force correspondingto the current value decreases the action of the biasing force to weakenthe joint force between the clutch plates 16 a. When the electromagneticforce exceeds the biasing force, the clutch plates 16 a separate fromeach other.

In addition, a clutch driving part 42 (changeover controlmeans/transmission inhibition means) of the controller 2 as will bedescribed later separates or joins the clutch plates 16 a of therotating shaft clutch 16 in accordance with the rotational speed(hereinafter referred to as rotational speed N) detected by therotational speed detector 18. More specifically, the rotational speed Nis compared with a predetermined rotational speed (hereinafter referredto as rotational speed N1). When the rotational speed N is less than therotational speed N1, the two clutch plates 16 a are separated. That is,a clutch operation current is supplied to the rotating shaft clutch 16.

When the two clutch plates 16 a are joined to each other to transmit therotation driving force of the first rotating shaft member 15 to thesecond rotating shaft member 17, the load for operating a dynamo 19 isgenerated on the second rotating shaft member 17. Therefore, when thewind power is weak in comparison with the load, the first rotating shaftmember 15 and the wind turbine blades 12 stop. Thus, when the rotationalspeed N is smaller than the rotational speed N1, the two clutch plates16 a are separated from each other so as not to transmit the loadgenerated on the second rotating shaft member 17 to the first rotatingshaft member 15, thereby preventing the first rotating shaft member 15and wind turbine blades 12 from stopping.

In addition, when the rotational speed N increases after the two clutchplates 16 a are separated from each other to rotate the wind turbineblades 12 without stopping, and the rotational speed N exceeds therotational speed N1 and further a rotational speed N2, the two clutchplates 16 a are again joined. That is, supply of the clutch operationcurrent to the rotating shaft clutch 16 is stopped. Consequently, theload on the first rotating shaft member 15 and the wind turbine blades12 disappear, the wind turbine blades 12 increases the rotational speedon the contrary, without stopping. Using the force of inertia that makesthe rotation continue, the first rotating shaft member 15 and the windturbine blades 12 can keep rotating without stopping even after the twoclutch plates 16 a are joined to each other.

By repeating the above-described operations alternately, even when thewind power weakens, the wind turbine blades 12 continue to rotatewithout stopping. The rotational speed N2 is obtained by adding acertain value to the rotational speed N1, and it is a rotational speedthat makes it possible to generate a voltage not less than a voltagevalue (hereinafter referred to as charging voltage V) for charging thebattery 4 as will be described later (see FIG. 10). When the voltagegenerated by the dynamo 19 is not more than the charging voltage V, thebattery 4 is not charged.

The second rotating shaft member 17 to which the rotation driving forceis transmitted through the above-described rotating shaft clutch 16, isprovided with a dynamo 19 (electric power generation means) of, e.g., athree-phase alternating type. The dynamo 19 outputs alternating electricpower in accordance with the rotational speed of the second rotatingshaft member 17. A short-circuit brake 21 is connected to the outputside of the dynamo 19. The short-circuit brake 21 includes short-circuitrelay 22 connected to the respective terminals of the dynamo 19. Eachshort-circuit relay 22 makes a switch unit open by energizing from thecontroller 2, and makes the switch unit close when energizing from thecontroller 2 is stopped. Thereby, the short-circuit relay 22short-circuit the output side of the dynamo 19 upon an abnormalcondition such as a trouble of the controller 2. Thus, the short-circuitbrake 21 generates a great load on the dynamo 19 to brake the rotationof the rotation support mechanism 14 by the wind turbine blades 12.

Further, a stopping device 20 for fixing the rotation support mechanism14 by a manual operation is provided on the lower portion of the secondrotating shaft member 17. The stopping device 20 includes an annularmember 20 a attached on the second rotating shaft member 17, and apressing member 20 b provided so as to be able to be brought intocontact with and separated from the outer circumferential surface of theannular member 20 a. Part of the pressing member 20 b is set on anon-illustrated fixed portion such as a stand or the ground. When thepressing member 20 b is pressed onto the annular member 20 a by a manualoperation, the stopping device 20 fixes the second rotating shaft member17 by a great braking force, as a result, the rotation of the rotationsupport mechanism 14 is completely stopped. Alternatively, the stoppingdevice 20 may be constructed such that it automatically operates inaccordance with operation instructions from an operation display unit 3as will be described later.

The wind turbine generator main body 1 constructed as described above isconnected to the controller 2. As illustrated in FIG. 1, the controller2 includes a control section 31 for controlling the wind turbinegenerator, and a rectifying section 32 for rectifying the alternatingelectric power output from the dynamo 19 of the wind turbine generatormain body 1, into direct electric power. The control section 31 includesa rotational speed inputting part 41, a clutch driving part 42, and ashort-circuit driving part 43. These parts 41 to 43 are connected to therotational speed detector 18 and the rotating shaft clutch 16 of thewind turbine generator main body 1, and the short-circuit brake 21,respectively.

The rotational speed inputting part 41 has a function of converting therotational speed signal from the rotational speed detector 18, into asignal form suitable for signal processing. The clutch driving part 42has a function of outputting a clutch driving signal to the rotatingshaft clutch 16 to control the operating condition of the rotating shaftclutch 16, that is, control the rotating shaft clutch 16 so as to weakor cancel the coupling force between the first and second rotating shaftmembers 15 and 17 of FIG. 2. The short-circuit driving part 43 has afunction of outputting a driving signal to each short-circuit relay 22of the short-circuit brake 21 upon a usual operation to fall the dynamo19 in a short-circuit state upon an abnormal condition.

In addition, the controller 2 includes an auxiliary charging operationpart 44, a charging control driving part 45, an inverter control part46, and an operation display inputting/outputting part 47. Thecontroller 2 further includes an arithmetic processing part 51 formonitoring and controlling the respective parts 41 to 47. Details of thearithmetic processing part 51 will be described later.

The above auxiliary charging operation part 44 is connected to theauxiliary charger 7 called DC power pack for charging the battery 4 withauxiliary electric power. As illustrated in FIG. 3, the auxiliarycharger 7 is integrally provided by being mounted on a single board orbeing accommodated in a casing. The auxiliary charger 7 is provided witha power supply input terminal 7 a, a power supply output terminal 7 b,and a signal input terminal 7 c. A commercial or industrial power supply71 is detachably connected to the power supply input terminal 7 a. Thebattery 4 is detachably connected to the power supply output terminal 7b. The auxiliary charging operation part 44 is detachably connected tothe signal input terminal 7 c.

The primary coil 72 a of a transformer 72 is connected to the abovepower supply input terminal 7 a. The secondary coil 72 b of thetransformer 72 is provided with a capacitor 73 for regulating current,and a bridge diode 74 for full-wave rectification of voltage changing inan alternating state. The bridge diode 74 is connected at its cathode tothe positive electrode of the battery 4 through the power supply outputterminal 7 b and at its anode to the negative electrode of the battery 4through the power supply output terminal 7 b. Thus, the auxiliarycharger 7 has a function that is changing the alternating electric powerfrom the power supply 71 into a predetermined voltage by transformer 72and then charging the battery 4.

In addition, the auxiliary charger 7 includes an auxiliary power supplyrelay 75. The auxiliary power supply relay 75 includes a switch 75 aprovided so as to form part of a current path of the primary coil 72 a,and a coil 75 b for opening and closing the switch 75 a. The switch 75 ais set such that the switch 75 a is open when the coil 75 b isenergized. The coil 75 b is connected to the auxiliary chargingoperation part 44 through the signal input terminal 7 c. Thus, theauxiliary charger 7 has a function of being able to switch betweencarrying-out and stopping of auxiliary charging of the battery 4 inaccordance with an operation signal from the auxiliary chargingoperation part 44.

As illustrated in FIG. 1, the battery 4 to be auxiliary-charged by theabove-described auxiliary charger 7 is connected also to the rectifyingsection 32 of the controller 2. The rectifying section 32 is soconstructed as to convert the alternating electric power from the dynamo19 of the wind turbine generator main body 1 into direct electric powerand charge the battery 4 with the direct electric power.

That is, as illustrated in FIG. 2, the rectifying section 32 includes abridge diode 33 connected to the dynamo 19; a charging capacitor 34connected in parallel to the anode and cathode of the bridge diode 33; adiode 35 connected to the bridge diode 33 downstream of the chargingcapacitor 34 in the same direction of the bridge diode 33; a chargingcontrol section 36 provided between the charging capacitor 34 and thediode 35 for controlling to switch between passing and interrupting ofcurrent; and a coil 37 provided downstream of the diode 35. The abovecharging control section 36 comprises a semiconductor switch such as atransistor. The charging control section 36 is connected to the chargingcontrol driving part 45 of FIG. 1. The charging control driving part 45outputs a charging control signal to control the time of energizing fromthe bridge diode 33 to the diode 35. The rectifying section 32constructed as described above is connected to the battery 4 and theinverter 5. The rectifying section 32 charges the battery 4 withelectric power of a charging voltage in accordance with the energizingtime controlled by the charging control section 36.

The above charging control section 36 comprises a semiconductor switchsuch as a transistor. The charging control section 36 is connected tothe charging control driving part 45 of FIG. 1. The charging controldriving part 45 outputs a charging control signal to control the time ofenergizing from the bridge diode 33 to the diode 35. The rectifyingsection 32 constructed as described above is connected to the battery 4and the inverter 5. The rectifying section 32 charges the battery 4 withelectric power of a charging voltage in accordance with the energizingtime controlled by the charging control section 36.

As illustrated in FIG. 1, the rectifier section 32 includes a dynamovoltage detector 38 for detecting the dynamo voltage of the alternatingelectric power input from the dynamo 19; and a charge condition detector39 (stored electric power detection means) for detecting a chargingvoltage, i.e., battery voltage, and charging current for charging thebattery 4 and a charging voltage stored in the battery 4. The rotationalspeed of the rotation support mechanism 14 also shows a change involtage of the electric power generated by the dynamo 19. That is, uponusual generation, it is substantially the same as the dynamo voltagedetected by the dynamo voltage detector 38. These detectors 38 and 39are connected to the arithmetic processing part 51. Each of the voltagedetectors 38 and 39 outputs a detected voltage to the arithmeticprocessing part 51.

The inverter control part 46 connected to the arithmetic processing part51 like the above-described charging control driving part 45 isconnected to the inverter 5. The inverter 5 has an output function ofconverting the direct electric power stored in the battery 4 intodomestic alternating electric power for example, and outputting thealternating electric power to the external load 6, and a function ofswitching between the operation and stop of the output function inaccordance with a signal from the inverter control part 46.

Further, the operation display inputting/outputting part 47 connected tothe arithmetic processing part 51 is detachably connected to theoperation display unit 3.

The operation display unit 3 will be described here. As illustrated inFIG. 4, the operation display unit 3 includes a display part 61 such asseven-segment LEDs or an LCD, a reset switch 62, and a displaychangeover switch 63 (operation means). The display unit 61 is designedsuch that operating conditions of the wind turbine generator can beshown with characters or numerical values. The operating conditionsinclude the rotational speed of the rotation support mechanism 14, i.e.,wind speed, obtained through the rotational speed inputting part 41, thedynamo voltage detected by the dynamo voltage detector 38, the chargingvoltage, i.e., the battery voltage, detected by the charge conditiondetector 39, and operating conditions of each of other units. The resetswitch 62 is for resetting the operation display unit 3.

The display changeover switch 63 set the display of operating conditionson the display unit 61 to be changeable by manual operation.

The operating conditions to be displayed include the rotational speed ofthe rotation support mechanism 14 (revolutions per minute in thefigure), dynamo voltage (generation voltage in the figure), chargingvoltage (battery voltage in the figure), and load current as electriccurrent being supplied to the external load 6, detected by the inverter5. These operating conditions are displayed on the display part 61 inorder with being changed over every time when the display changeoverswitch 63 is depressed. In FIG. 7, the dynamo voltage is beingdisplayed. In addition, a condition that 100 V output to the externalload 6 is ensured is indicated (100 V output in the figure).

In addition, the display changeover switch 63 set a normal mode (mode 0)wherein the output of the inverter 5 is always kept, a save mode (mode1) wherein the inverter control part 46 stops the output of the inverter5 when the rotational speed of the rotation support mechanism 14 is notmore than a set value, and an interval save mode (mode 2) wherein theinverter control part 46 stops the output of the inverter 5 when acertain time period has elapsed after the rotational speed of therotation support mechanism 14 is not more than the set value, to bechangeable by manual operation. By depressing the display changeoverswitch 63 for a long time of 5 seconds or more, the modes are changedover in order. The set contents are stored in a non-illustrated memory.

The operation display unit 3 includes a control part comprising anarithmetic part, a memory, and so on, which are not illustrated. Inaddition to a function of controlling the operation display unit 3itself, the control part has a function of communication with thecontroller 2, in the form of a program. Alternatively, each function inthe operation display unit 3 may be realized by the form of hardware inplace of the form of software.

Likewise, the arithmetic processing part 51 of the controller 2 includesan arithmetic part and a memory, which are not illustrated, and hasvarious functions for controlling the wind turbine generator, in theform of programs.

The arithmetic processing part 51 has an auxiliary charging processingfunction, an abnormal operation braking function, a rotationaccelerating function, a low-voltage charging function, a batteryprotecting function, and so on. The auxiliary charging processingfunction is a function of monitoring the charging voltage detected bythe charging condition detector 39 and permitting the auxiliary charger7 to charge the battery 4 with auxiliary electric power when thecharging voltage is less than a first predetermined value. The abnormaloperation braking function is a function of energizing the short-circuitrelay 22 of the short-circuit brake 21 to be open upon a normaloperation so that the alternating electric power of the dynamo 19 can besupplied to the bridge diode 33, and short-circuiting the output of thedynamo 19 to generate braking force on the dynamo 19 when energizing isstopped because of an abnormal operation. The rotation acceleratingfunction is a function of releasing the coupling state of the rotatingshaft clutch 16 so that only the first rotating shaft member 15 can berotated, when the rotational speed of the rotation support mechanism 14is less than a second predetermined value because of a decrease in windpower, and restoring the coupling state of the rotating shaft clutchwhen the rotational speed of the first rotating shaft member 15 isincreased to not less than a certain value. The low-voltage chargingfunction is a function of performing charging control for switching thecharging control section 36 between the ON state and OFF state when therotational speed of the rotation support mechanism 14 is not less than athird predetermined value, and keeping the charging control section 36in the ON state when the rotational speed has lowered to less than thethird predetermined value. The battery protecting function is a functionfor preventing the battery 4 from being over discharged. It is afunction of ON/OFF-controlling the power output unit of the inverter 5on the basis of the rotational speed of the rotation support mechanism14 in accordance with each operation mode stored in the memory.

Operations of the wind turbine generator of the above-describedconstruction will be described.

Upon general operation stop, as illustrated in FIG. 2, energizing to thedeenergization operation type rotating shaft clutch 16 is stopped sothat the rotating shaft clutch 16 falls in a strong coupling state.Thereby, the first rotating shaft member 15 and the second rotatingshaft member 17 of the rotation support mechanism 14 are united by therotating shaft clutch 16. In addition, energizing to the short-circuitrelay 22 of the short-circuit brake 21 is stopped so that the dynamo 19falls in a short-circuit state. Thereby, the dynamo 19 is in a statethat the operation of the dynamo 19 requires a large load. As a result,even when a large rotation driving force is applied to the rotationsupport mechanism 14 by a wind, as the rotation support mechanism 14rotates the dynamo 19 at a high speed to be operated, a heavy load actsas a braking force to the rotation of the rotation support mechanism 14,so that a high-speed rotation of the rotation support mechanism 14 isinhibited.

Further, upon a special operation stop such as a strong wind orinspection, a braking force in the stopping device 20 is generated.Thereby, the second rotating shaft member 17 of the rotation supportmechanism 14 is fixed so that the rotation of the rotation supportmechanism 14 is completely stopped.

Next, upon an operation, after the operation display unit 3 is connectedto the controller 2 at need, the controller 2 and the operation displayunit 3 are powered on. In the controller 2, energizing the rotatingshaft clutch 16 is started. Thereby, the coupling state of the rotatingshaft clutch 16 is released so that the first rotating shaft member 15is separated from the second rotating shaft member 17. As a result, thefirst rotating shaft member 15 is in a state of being rotatable relativeto the second rotating shaft member 17. Thus, even when only a weak windstrikes the wind turbine blades 12, the first rotating shaft member 15can rapidly increase in its rotational speed. In addition, theshort-circuit state of the dynamo 19 is released by energizing theshort-circuit brake 21 so that the alternating electric power generatedby the dynamo 19 can be supplied to the controller 2. On the other hand,in the operation display unit 3, an operating condition of the controlsection 31, that is, the rotational speed of the first rotating shaftmember 15 for example is displayed with a numerical value or the like.

Next, the controller 2 operates such that the arithmetic processing part51 effects the auxiliary charging processing function, the abnormaloperation braking function, the rotation accelerating function, thelow-voltage charging function, the battery protecting function, and soon.

(Rotation Accelerating Function)

First, the rotation accelerating function will be described withreference to FIG. 5. In S301 of FIG. 5, the rotational speed N of thefirst rotating shaft member 15 is monitored. The flow then advances toS302, wherein it is judged whether or not the rotational speed N is lessthan a rotational speed N2. When the rotational speed N is less than therotational speed N2 (S302: Yes), the flow advances to S303, wherein itis judged whether or not the rotational speed N is less than arotational speed N1. When the rotational speed N is less than therotational speed N1 (S303: Yes), that is, when the wind is weak, theflow advances to S304, wherein the rotating shaft clutch is set ON. Thatis, clutch operation current is supplied to the rotating shaft clutch 16so that the clutch plates 16 a are separated from each other. As aresult, because the first rotating shaft member 15 rotates under no loadcondition, it can rotate even upon a weak wind. Afterward, the flowreturns to S301.

When the rotational speed N is not less than the rotational speed N1(S303: No), that is, when the wind is not weak, the flow returns toS301. When the rotational speed N is not less than the rotational speedN2 (S302: No), the flow advances to S305, wherein it is judged whetheror not the rotating shaft clutch 16 is ON. When the rotating shaftclutch 16 is ON (S306: Yes), the rotating shaft clutch 16 is set OFF.That is, the supply of the clutch operation current to the rotatingshaft clutch 16 is stopped so that the clutch plates 16 a are joined toeach other. Even when the clutch plates 16 a are joined to each other,because the inertia of the first rotating shaft member 15 acts, therotation support mechanism 14 in which the first and second rotatingshaft members 15 and 17 are united rotates at a relatively high speed.When the rotating shaft clutch 16 is not ON (S306: No), the flow returnsto S301.

That is, when the wind is weak, the rotational speed of the rotationsupport mechanism 14 decreases due to the load for operating the dynamo19. In this case, if the dynamo voltage that the dynamo 19 generates bythe rotation of the rotation support mechanism 14 is lower than thecharging voltage V of the battery 4, the battery 4 can not be charged.Therefore, as illustrated in FIG. 10, when the rotational speed N hasdecreased to less than the rotational speed N1, the coupling state ofthe rotating shaft clutch 16 is released by energizing the rotatingshaft clutch 16 so that only the first rotating shaft member 15 canrotate. Thus, the first rotating shaft member 15 is in a state of beingable to be accelerated in a short time even upon a weak wind. When therotational speed N has increased to not less than the rotational speedN2, that is, when it has reached a rotational speed at which a voltageof not less than the charging voltage that can charge the battery 4 canbe generated, the coupling state of the rotating shaft clutch 16 isrestored to restart the generation by the dynamo 19. Thereby, even incase of a weak wind, alternating electric power of a high voltage can beintermittently supplied to the controller 2.

(Low-Voltage Charging Function)

The alternating electric power supplied to the controller 2 as describedabove is full-wave-rectified in the bridge diode 33 and then smoothed bya smoothing circuit made up of a charging capacitor 34, a diode 35, anda coil 37, to be stored in the battery 4. The electric power stored inthe battery 4 is used as the power supply of the controller 2. Inaddition, the electric power is converted into alternating electricpower by the inverter 5 to be used as the power supply of the externalload 6.

Upon this, as shown in FIG. 6, the charging voltage and charging currentfor charging the battery 4 are controlled by the charging controlsection 36. That is, when the rotational speed of the rotation supportmechanism 14 is not less than the third predetermined value, the battery4 is judged to be charged with a charging voltage considerably higherthan the rated voltage of the battery 4. Thus, charging control is donein which the charging control section 36 is switched between the ONstate and the OFF state so as to lower the charging voltage.

That is, when the charging voltage is judged to be not less than thethird predetermined value because of strong wind power, supply ofelectric power to the battery 4 (ON state of the charging controlsection 36) and stop of the supply (OFF state of the charging controlsection 36) are repeated. In the ON state of the charging controlsection 36, large discharge current corresponding to the electric powerstored in the charging capacitor of FIG. 2 is supplied as chargingcurrent to the battery 4. On the other hand, in the OFF state of thecharging control section 36, small current flowing in a closed circuitcomprising the coil 37 and the diode 35 is supplied as charging currentto the battery 4. As a result, under a high charging voltage of not lessthan the third predetermined value, the battery 4 is charged withcharging current being throttled.

On the other hand, when the rotational speed has decreased to less thanthe third predetermined value, the battery 4 is judged to be chargedwith a charging voltage near the rated voltage of the battery 4. Thus,charging control is done to keep the charging control section 36 in theON state so that the battery 4 is charged with charging current as largeas possible.

That is, when the charging voltage is judged to be less than thepredetermined value because of a weak wind power, supply of electricpower to the battery 4 (ON state of the charging control section 36) iscontinued. Thus, the whole current rectified by the bridge diode 33 issupplied as charging current to the battery 4. As a result, under a lowcharging voltage, the battery is charged with charging current as largeas possible.

(Auxiliary Charging Processing Function)

As illustrated in FIG. 1, while the battery 4 is charged, the chargingvoltage detected by the charging condition detector 39 is monitored.When the charging voltage has decreased to less than the firstpredetermined value, charging the battery 4 with auxiliary electricpower by the auxiliary charger 7 is permitted.

That is, as illustrated in FIG. 3, when the charging voltage is not lessthan the first predetermined value, the switch 75 a is set to an openstate by energizing the auxiliary power supply relay 75 so thatauxiliary charging the battery 4 is inhibited. On the other hand, whenthe charging voltage has decreased to less than the first predeterminedvalue, the charging voltage of the battery 4 (battery voltage) is judgedto considerably lower. Thus, energizing the auxiliary power supply relay75 is stopped. The auxiliary power supply relay 75 stopped to beenergized changes over the switch 75 a from the open state to the closestate. Thereby, the alternating electric power from the power supply 71is supplied to the transformer 72. After the electric power is changedinto a predetermined voltage by the transformer 72, auxiliary electricpower made into constant current by the capacitor 73 is generated.Auxiliary charging the battery 4 is performed with the auxiliaryelectric power. The charging current to the battery 4 is determined by Iomega CE, where omega=2 pi f, C represents the capacitance microfarad ofthe capacitor 73, and E represents the charging voltage. In addition,even when the controller 2 can not operate as a result of the chargingvoltage of the battery 4 having extremely lowered, because energizingthe auxiliary power supply relay 75 is stopped, auxiliary charging thebattery 4 by the auxiliary charger 7 is performed.

(Abnormal Operation Braking Function)

As illustrated in FIG. 2, when the wind turbine generator is in normaloperation, the short-circuit relay 22 of the short-circuit brake 21 isenergized to be open. The alternating electric power from the dynamo 19is supplied to the rectifying section 32 of the bridge diode 33 and soon to charge the battery 4. On the other hand, when the controller 2 isbrought into an emergency stop because of an abnormal condition such aswear or damage of parts, all signal outputs being output to the windturbine generator main body 1 and so on are stopped. As a result,because energizing the short-circuit relay 22 of the short-circuit brake21 is stopped, the dynamo 19 is brought into a short-circuited state.

When energizing the rotating shaft clutch 16 is stopped, the clutchplates 16 a are brought into a strongly coupled state because therotating shaft clutch 16 is a deenergization operation type. Thereby,the first rotating shaft member 15 and the second rotating shaft member17 of the rotation support mechanism 14 are united by the rotating shaftclutch 16. Thus, the rotational speed of the rotation support mechanism14 is rapidly decreased due to the heavy load by the dynamo 19 in theshort-circuited state.

(Battery Protecting Function)

As described before, the battery protecting function has three modes,i.e., the normal mode, the save mode, and the interval save mode. Theseare set by the display changeover switch 63 of the operation displayunit 3. When the battery protecting function is set to the normal mode(mode 0), the output of the inverter 5 is always maintained. In a stateof the battery 4 having been over discharged, the output of the inverter5 is stopped. When the battery protecting function is set to the savemode (mode 1), the inverter control part 46 stops the output of theinverter 5 if the rotational speed of the rotation support mechanism 14is not more than a set value, for example, 50 rpm. When the batteryprotecting function is set to the interval save mode (mode 2), theinverter control part 46 stops the output of the inverter 5 if therotational speed of the rotation support mechanism 14 is not more than aset value, for example, 50 rpm, and a predetermined time period, forexample, one hour, has elapsed. In the save mode and the interval savemode, after the output of the inverter 5 is stopped, the output of theinverter 5 is restarted by keeping not less than the rotational speed(for example, 50 rpm) of the rotation support mechanism 14 for apredetermined time, for example, five minutes, by a certain wind power.When the battery 4 has been fully charged, the output of the inverter 5is maintained. At this time, the rotational speed of the rotationsupport mechanism 14 is detected as a voltage reference of the electricpower to be generated by the dynamo 19. Therefore, not the rotationalspeed of the rotation support mechanism 14 but the dynamo voltage may bedetected, or the charging voltage may be detected.

Next, the operation procedure of the battery protecting function will bedescribed with reference to the flowchart of FIG. 7. The flow advancesto Step S101, wherein the rotational speed detector 18 detects therotational speed of the rotation support mechanism 14. The chargingvoltage of the battery 4 is determined by the rotational speed of therotation support mechanism 14. Afterward, the flow advances to StepS102, wherein it is judged whether or not a time period of one hour ormore has elapsed in a state that the rotational speed of the rotationsupport mechanism 14 is 0 to 50 rpm. When the time period of one hour ormore is judged not to have elapsed in the state that the rotationalspeed of the rotation support mechanism 14 is 0 to 50 rpm (S102: NO),the flow again advances to Step S101 and then the above-describedprocedure is repeated. When the time period of one hour or more isjudged not to have elapsed in the state that the rotational speed of therotation support mechanism 14 is 0 to 50 rpm (S102: YES), the flowadvances to Step S103.

In Step S103, it is judged whether or not the mode set in the memory isthe normal mode (mode 0). When the set mode is judged to be the normalmode (mode 0) (S102: YES), the output of the inverter 5 is maintainedwithout any change and the flow again advances to Step S101. When theset mode is judged not to be the normal mode (mode 0) (S102: NO), theflow advances to Step S104, wherein it is judged whether or not the setmode is the save mode (mode 1). When the set mode is judged to be thesave mode (mode 1) (S104: YES), the flow advances to Step S106, whereinthe output of the inverter 5 is immediately stopped. When the set modeis judged not to be the save mode (mode 1) (S104: NO), then the set modeis judged to be the interval save mode (mode 2) and the flow advances toStep S105, wherein an interval of a predetermined time is set.Afterward, the flow advances to Step S106, wherein the output of theinverter 5 is stopped.

Afterward, the flow advances to Step S107, wherein it is judged whetheror not a time period of five minutes or more has elapsed in a state thatthe rotational speed of the rotation support mechanism 14 is not lessthan 50 rpm. When the time period of five minutes or more is judged tohave elapsed in the state that the rotational speed of the rotationsupport mechanism 14 is not less than 50 rpm (S107: YES), the flowadvances to Step S110. When the time period of five minutes or more isjudged not to have elapsed in the state that the rotational speed of therotation support mechanism 14 is not less than 50 rpm (S107: NO), theflow advances to Step S108, wherein it is judged whether or not a userhas performed a reset operation. The reset operation means an operationof depressing the reset switch 62 of the operation display unit 3. Whenthe user is judged not to have performed the reset operation (S108: NO),the flow again advances to Step S107. When the user is judged to haveperformed the reset operation (S108: YES), the flow advances to StepS110. In Step S110, the operation mode is set to the mode 0 and theoutput of the inverter 5 is set ON. Afterward, the flow again advancesto Step S101.

As described above, the power supply unit of this embodiment includesthe battery 4 (storage means) for storing electric power that is usedfor operations of various devices, charging means (the dynamo 19, therotation support mechanism 14, and the rectifying section 32) forconverting natural energy into electric energy and supplies electricpower of the electric energy to the battery 4 to be charged, thecharging control section 36 (charging changeover means) for changingover between supply and stop of the electric power from the chargingmeans to the battery 4, and charging changeover control means (thecharging control driving part 45, and the low-voltage charging functionof the arithmetic processing part 51) for converting the chargingcontrol section 36 such that supply and stop of the electric power arerepeated when the charging voltage for charging the battery 4 withelectric power is not less than the third predetermined value, andcontinues supply of the electric power when the charging voltage is lessthan the third predetermined value.

Here, various devices of the external load 6 include electric devicessuch as the controller 2 of the wind turbine generator and arefrigerator of the external load 6; light and heat devices such aselectric lights and air conditioners; and so on. The natural energyincludes any energy existing in the natural world, such as wind power, asolar cell, water power, and wave power.

According to the above construction, when the charging voltage forcharging the battery 4 is not less than the third predetermined valuebecause of large natural energy, supply and stop of electric power tothe battery 4 are repeated and thereby the battery 4 is charged withcharging current being throttled under a high charging voltage. On theother hand, when the charging voltage for charging the battery 4 is lessthan the third predetermined value because of small natural energy, bycontinuing supply of electric power to the battery 4, the battery 4 ischarged with charging current as large as possible under a low chargingvoltage. Therefore, even in case that the charging voltage may changewidely due to increase/decrease of the natural energy, the battery 4 canbe efficiently charged.

In addition, an electric power supply of the present embodiment includesthe battery 4 (storage means) for storing electric power that is usedfor operations of various devices, charging means (the dynamo 19, therotation support mechanism 14, and the rectifying section 32) forconverting natural energy into electric energy and supplies electricpower of the electric energy to the battery 4 to be charged, theauxiliary charger 7 (auxiliary charging means) for charging the battery4 with auxiliary electric power, and charging control means (anauxiliary charging operation part 44 and the low-voltage chargingfunction of the arithmetic processing part 51) for monitoring thecharging voltage of the battery 4 and permitting that the auxiliarycharging means charge auxiliary electric power to the battery 4 when thecharging voltage is less than a predetermined value.

According to the above construction, because the auxiliary charger 7charges the battery 4 with auxiliary electric power when the chargingvoltage of the battery 4 has lowered to less than a predetermined value,the charging voltage of the battery 4 is always kept to the chargingvoltage of not less than the predetermined value. Thereby, a trouble canbe prevented in which various devices such as the controller 2erroneously operate or can not operate due to electric power of a toolow voltage. In addition, the battery 4 can be prevented from being overdischarged, besides a trouble of operation stop of the controller 2 canbe prevented. As a result, when a wind turbine generator provided withthis power supply unit is used, because the battery 4 can be surelycharged even in a area where the wind is weak, the wind turbinegenerator can be operated with high reliability.

In addition, as illustrated in FIG. 3, the auxiliary charger 7 of thisembodiment comprises the power supply 71 (auxiliary power supply means)that outputs auxiliary electric power of direct current of apredetermined voltage, and the auxiliary power supply relay 75(changeover means) in which supply and stop of auxiliary electric powerto the battery 4 can be changed over by the charging control means.Thus, the auxiliary charger 7 of the power supply unit can be easilyconstructed.

As illustrated in FIG. 2, the power supply unit further comprises thebattery 4 (storage means) for storing electric power that is used foroperations of various devices outputted from the bridge diode 33. Thus,the battery 4 can efficiently charge a high even in case of smallnatural energy.

In addition, a wind turbine generator comprises a power supply unit asdescribed above. According to this feature, the wind turbine generatorcan be efficiently operated in an environment that wind power may changewidely

According to the above construction, even under conditions of a weakwind, by alternately repeating transmission and interruption of the windenergy to the dynamo 19, the generation efficiency of the dynamo 19 canbe improved. In case of a weak wind, because some load is applied to therotation support mechanism 14 due to the dynamo 19 when the wind poweris transmitted to the dynamo 19, there is a fear that the rotationsupport mechanism 14 is stopped.

By separating the first and second rotating shaft members 15 and 17 fromeach other by the rotating shaft clutch 16, the above load can beprevented from being transmitted to the first rotating shaft member 15.Therefore, the first rotating shaft member 15 and the wind turbineblades 12 continue to rotate without stopping. Further, there can bemade a state that the rotational speed can raise. By using the force ofinertia at this time, a rotation driving force larger than the generatedload can be obtained even when the clutch operation current to therotating shaft clutch is interrupted to couple the first and secondrotating shaft members 15 and 17 to each other. Therefore, the firstrotating shaft member 15 and the wind turbine blades 12 can rotatewithout stopping. By repeating this operation, generation of electricpower can be done without stopping. In addition, the rotation drivingforce can thereby be raised as much as possible. Thus, even in case of aweak wind, the dynamo 19 can sufficiently generate electric power.

In addition, when the rotational speed N of the wind turbine blades 12is more than the rotational speed N2, the rotation clutch is operated tocouple the clutch plates 16 a to each other. Thereby, the wind turbineblades 12 are rotated till a required rotation driving force isobtained, that is, the rotational speed of the wind turbine blades 12reaches a rotational speed at which a voltage not less than the chargingvoltage for charging the battery 4 can be generated. Thus, the dynamo 19can efficiently generate electric power. Further, because wind power asa kind of natural energy is converted into rotation driving force withthe wind turbine 11, because the magnitude of the driving force ismeasured from the rotational speed of the wind turbine blades 12, it canbe constructed in a simple structure in comparison with anotherconstruction.

According to the above construction, because the output of the electricpower can be stopped by the battery protecting function when the voltageof the electric power generated by the dynamo 19 is insufficient, thebattery 4 can be prevented from being over discharged. Thus, the battery4 can be protected.

In addition, in this embodiment, because the rotational speed detector18 detects the rotational speed of the rotation support mechanism 14,the electric power generated by the dynamo 19 can be detected easily andinexpensively.

Further, although this embodiment is a system of wind turbine generationin which the rotation support mechanism 14 is rotated by wind power tomake the dynamo 19 generate electric power, the battery 4 can beprevented from being over discharged even in the wind turbine generationunstable in generated electric power.

In addition, in this embodiment, because the inverter control part 46controls the electric power outputting unit provided in the inverter 5,there is no need of providing separate outputting means.

In addition, in this embodiment, in the interval save mode (mode 2) ofthe battery protecting function, because the output of the electricpower to the external load 6 after a predetermined time period elapsesafter the rotational speed of the rotation support mechanism 14 lowers,the user can get him or herself ready for the stop of the output of theelectric power.

Further, in this embodiment, the display changeover switch 63 isprovided so that the modes of the battery protecting function can beeasily changed over, flexibly coping is possible in accordance withconditions.

In addition, in this embodiment, because the revolutions, the dynamovoltage, the charging voltage, and the load current of the rotationsupport mechanism 14 can be displayed on the display unit 61, the usercan easily check the operating conditions.

In this embodiment, in the save mode or the interval save mode of thebattery protecting function, when the battery 4 has not been fullycharged, it is judged on the basis of the dynamo voltage obtained fromthe rotational speed of the rotation support mechanism 14 whether or notthe output of the inverter 5 should be stopped. However, it may bejudged on the basis of a change in electric power stored in the battery4 whether or not the output of the inverter 5 should be stopped.Thereby, stable electric power can be supplied to the external load 6with preventing the battery 4 from being over discharged.

Although the present invention has been described on the basis of apreferred embodiment, changes can be made within a scope not deviatingthe spirit of the present invention. That is, the present invention mayhave a construction in which a charging changeover control meanscontrols a charging control section 36 such that supply and stop of theelectric power are repeated at stop time intervals corresponding to acharging voltage for charging the battery 4 with electric power.

According to the above construction, when the charging voltage forcharging the battery 4 is raised because of large natural energy, thesupply time is shortened because of an increase in stop time interval.Thus, the battery 4 is charged with charging current being throttled. Onthe other hand, when the charging voltage for charging the battery 4 islowered because of small natural energy, the supply time is elongatedbecause of a decrease in stop time interval. Thus, the battery 4 ischarged with charging current as large as possible under a low chargingvoltage. Therefore, even in case that the charging voltage may changewidely due to increase/decrease of the natural energy, the battery 4 canbe efficiently charged.

In addition, the present invention may have a construction in whichcharging changeover control means controls a charging control section 36(charging changeover means) such that supply and stop of the electricpower are repeated at stop time intervals corresponding to a chargingvoltage for charging the battery 4 with electric power when the chargingvoltage is not less than a predetermined value, and continues supply ofelectric power when charging voltage is less than the predeterminedvalue.

According to the above construction, when the charging voltage forcharging the battery 4 is not less than the third predetermined value,supply and stop of electric power to the battery 4 are repeated andthereby the battery 4 is charged with charging current being throttledunder a high charging voltage. On the other hand, when the chargingvoltage for charging the battery 4 is less than the third predeterminedvalue, by continuing supply of electric power to the battery 4, thebattery 4 is charged with charging current as large as possible under alow charging voltage.

Further, when the charging voltage for charging the battery 4 is raisedunder the condition that the charging voltage is not less than the thirdpredetermined value, the supply time is shortened because of an increasein stop time interval. Thus, the battery 4 is charged with chargingcurrent being throttled. On the other hand, when the charging voltagefor charging the battery 4 is lowered under the condition that thecharging voltage for charging the battery 4 is not less than thepredetermined value, the supply time is elongated because of a decreasein stop time interval. Thus, the battery 4 is charged with chargingcurrent as large as possible under a low charging voltage. Therefore,even in case that the charging voltage may change widely due toincrease/decrease of the natural energy, the battery 4 can beefficiently charged.

In addition, the power supply unit of this embodiment is so constructedthat the charging changeover control means obtains the charging voltageon the basis of the magnitude of natural energy. Thus, the chargingvoltage can be easily obtained. The wind turbine generator comprises apower supply unit having each construction as described above, therebythe wind turbine generator easy to be influenced by a change in naturalenvironment can be efficiently operated.

Although the present invention has been described on the basis of apreferred embodiment, changes can be made within the scope not deviatingfrom the spirit of the present invention. That is, the auxiliary charger7 of the embodiment is so constructed as to convert alternating electricpower supplied from the external power supply 71, into direct auxiliaryelectric power with the transformer 72 and the rectifying circuit, andthen charge the battery 4 with the direct auxiliary electric power.However, the present invention is not limited to this. That is, theauxiliary charger 7 may be a capacitor having a large capacity thatstores direct electric power supplied to the power supply 71 such as asolar cell. Otherwise, the auxiliary charger 7 may be a DC/DC converterthat converts direct electric power of a solar cell or the like intodirect current of a predetermined voltage to be output.

In addition, in this embodiment, the auxiliary power supply relay 75 isused as switching means. However, the present invention is not limitedto this. It may be a semiconductor switch such as a transistor or athyristor. Further, the switching means such as the auxiliary powersupply relay 75 may be provided on the secondary coil 72 b of thetransformer 72. In addition, the transformer 72 may be a center taptype. In this case, the bridge diode 74 can be made up of two diodes. Inaddition, the auxiliary charger 7 may have a construction in which theswitching means such as the auxiliary power supply relay 75 is disposedon the secondary coil 72 b and the capacitor 73 is disposed on theprimary coil 72 a.

In addition, as shown in FIG. 8, the power supply unit may comprise thebattery 4 (storage means) for storing electric power that is used foroperations of various devices, the charging means of FIG. 1 (the dynamo19 and the rectifying section 32) for converting wind energy as naturalenergy into electric power and charges the battery 4 with the electricpower, and an auxiliary charger 80 (auxiliary charging means) forcharging the battery 4 with auxiliary electric power by a chargingvoltage of not less than a predetermined value. The auxiliary charger 80is the same as one in which the auxiliary power supply relay 75 and thecapacitor 73 are eliminated from the above-described circuitconstruction of FIG. 3. In the auxiliary charger 80, the coils of thetransformer 72 are set such that the maximum value of the auxiliaryvoltage full-wave-rectified by the bridge diode 74 is around apredetermined value, such as 22 V, for example.

According to the above construction, as shown in FIG. 9, when thecharging voltage of the battery 4 has lowered to less than thepredetermined value such as 22 V of the auxiliary voltage, the auxiliarycharger 80 charges the battery 4 with auxiliary electric power. Thus,the charging voltage of the storage means is always kept at not lessthan the predetermined value. Further, according to the aboveconstruction, the storage means can be charged with auxiliary electricpower with a small number of parts. The transformer 72 is preferablyprovided with transformer taps for changing the output voltage intovalues of, for example, 12 V, 22 V, 48 V, etc. In this case, theauxiliary voltage can be easily changed in accordance with thespecification of the battery 4.

This embodiment has a construction for wind turbine generation in whichthe rotation support mechanism 14 is rotated by wind power to obtainelectric power. However, the present invention is not limited to theconstruction. The present invention may have a construction in which therotation support mechanism 14 is rotated by another kind of energy suchas water power. Otherwise, the present invention may not comprise therotation support mechanism 14 but comprise a generator to obtainelectric power with a solar cell or the like.

In addition, this embodiment comprises the inverter 5 and the electricpower outputting unit of the inverter 5 is so controlled as to supplyelectric power to the external load 6 connected to the electric poweroutputting unit. However, the present invention is not limited to such aconstruction. The electric power outputting unit may be providedseparately. In this case, electric power may be directly supplied fromthe electric power outputting unit to the external load not through theinverter.

Further, in this embodiment, the normal mode and the interval save modeare provided as the battery protecting function, and the modes can beselectively carried out. However, the present invention is not limitedto this construction. One of those modes may be provided. Further, thepresent invention has a construction in which only the save mode may becarried out.

In addition, in this embodiment, the operation display unit 3 includesthe display part 61 where each operating condition is displayed.However, the present invention is not limited to this construction.Another operating condition may be displayed, or any condition may notbe displayed.

In addition, in this embodiment, when the rotational speed of therotating shaft clutch exceeds the rotational speed N2, the first andsecond rotating shaft members are coupled to each other. However, thefirst and second rotating shaft members may be coupled to each other ata certain interval when the rotational speed N once exceeds therotational speed N1. In addition, in the above embodiment, the generatorusing wind power has been described. However, the present invention maybe a generator using water power or another kind of natural energy.Further, in the above embodiment, the wind turbine is rotated to convertnatural energy into kinetic energy. However, energy conversion may beperformed using another kind of member such as a piston thatreciprocates vertically.

Second Embodiment

Next, a second embodiment of the present invention will be describedwith reference to FIGS. 11 to 13. A wind turbine generator of thisembodiment differs from that of the first embodiment in a feature thatthe rotating shaft clutch is an energisation operation type.Hereinafter, only the different feature will be described. The samecomponents as in the first embodiment are denoted by the same referencenumerals as in the first embodiment, thereby omitting the description.

First, a rotating shaft clutch will be described.

As illustrated in FIG. 11, a rotating shaft clutch 16 interposed betweenrotating shaft members 15 and 17 is an energisation operation type. Morespecifically, the rotating shaft clutch 16 includes two clutch plates 16a, a non-illustrated spring member for biasing the clutch plates 16 a soas to separate from each other, and a coil member 16 b for generatingelectromagnetic force in the direction opposite to the biasing force ofthe spring member. In this construction, when a clutch operation currentis supplied, the electromagnetic force corresponding to the currentvalue decreases the action of the biasing force to increase the couplingforce (clutch force) between the clutch plates 16 a. When theelectromagnetic force exceeds the biasing force, the clutch plates 16 aare coupled to each other so that the rotation driving force of thefirst rotating shaft member 15 can be sufficiently transmitted to thesecond rotating shaft member 17. On the other hand, when no clutchoperation current is supplied, the biasing force of the spring decreasesthe coupling force between the clutch plates 16 a so that the clutchplates 16 a separate from each other.

An auxiliary power supply 16 c is connected to the coil member 16 b. Aconnection relay 16 d is provided between the coil member 16 b and theauxiliary power supply 16 c. The connection relay 16 d is adeenergization operation type. When the controller 2 is in a usualoperation, a signal is sent to the connection relay 16 d to open theconnection relay 16 d. Therefore, no current is supplied from theauxiliary power supply 16 c to the coil member 16 b. On the other hand,when the controller 2 is under an abnormal condition, the signal to theconnection relay 16 d is stopped to close the connection relay 16 d.Thus, current starts to be supplied from the auxiliary power supply 16 cto the coil member 16 b. At this time, the deenergization type coilmember 16 b is in a close state and the first and second rotating shaftmembers 15 and 17 are coupled to each other. Therefore, although thiswill be described later, when a short-circuit brake 21 operates upon anabnormal condition, a wind turbine 11 is stopped. The other constructionand function are the same as those in the first embodiment and thus thedescription is omitted.

Next, in the above-described construction, as for an operation of thewind turbine generator, an operating method of the rotating shaft member16 upon start of operation, which differs from the first embodiment,will be described in detail. As shown in FIG. 12(a), as the rotationalspeed N of the wind turbine 11 increases, the obtained rotation drivingforce increases. That is, obtained electric power increases.Conventionally, as shown in FIG. 12(b), when clutch operation current isonce supplied to the rotating shaft clutch 16, a certain quantity ofclutch operation current is always supplied. Thus, a great deal ofclutch operation current is required. In this case, upon a weak wind forexample, because the rotational speed N increases slow, it requires along time to obtain a voltage for charging. Therefore, if the clutchoperation current is always supplied to the rotating shaft clutch 16,there is no considerable difference between the electric power obtainedby the generation and the electric power consumed. This is noteffective.

In addition, as shown in FIG. 12(c), in case that a large clutchoperation current is supplied only upon operation of the rotating shaftclutch and the supply of the clutch operation current is decreased afterthe operation of the rotating shaft clutch, the first and secondrotating shaft members 15 and 17 slip on each other when the rotationalspeed N has increased. This is caused by the fact that the rotationalspeed of the first rotating shaft member 15 increases as the rotationalspeed N increases, and the rotational speed of the first rotating shaftmember 15 exceeds the frictional force acting between the clutch plates16 a interconnecting the first and second rotating shaft members 15 and17.

Therefore, in this embodiment, first, in S401 of FIG. 13, the rotationalspeed detector 18 detects the rotational speed N of the first rotatingshaft member 15. The flow then advances to S402, wherein it is judgedwhether or not the rotational speed N is not less than a rotationalspeed N1. When the rotational speed N is less than the rotational speedN1 (S402: No), the flow returns to S401. This procedure is repeated tillthe rotational speed N increases to not less than the rotational speedN1. That is, the first rotating shaft member 15 rotates under acondition of no load and thus the rotational speed N can increase. Whenthe rotational speed N is not less than the rotational speed N1 (S402:Yes), the flow advances to S403, wherein clutch operation current issupplied to the rotating shaft clutch 16. At this time, as shown in FIG.12(d), the maximum clutch operation current is supplied in order thatthe clutch plates 16 a of the rotating shaft clutch 16 are surelycoupled to each other. The rotational speed N1 is a rotational speed atwhich the rotation never stops even when the first and second rotatingshaft members 15 and 17 have been united to each other, that is, a loadby coupling is generated.

After the current is supplied to the coil member 16 b for apredetermined time, in S404, the current is decreased such that thevalue of the current never reaches zero. At this time, even when thecurrent has been decreased, the first and second rotating shaft members15 and 17 can rotate as one body due to the frictional force between theclutch plates 16 a. As the rotational speed N of the wind turbine 11increases, in S405, the current to be supplied is increased accordingly.Because the clutch operation current is increased as the rotationalspeed increases, the first and second rotating shaft members 15 and 17can rotate as one body.

The rate of the increase in the clutch operation current is determinedin the arithmetic processing part 51 of FIG. 1. When the frictionalforce acting between the clutch plates 16 a and the rotational force ofthe first rotating shaft member 15 are balanced, the first and secondrotating shaft members 15 and 17 rotate as one body. As described above,the rotational force increases as the rotational speed N of the firstrotating shaft member 15. Thus, to balance the forces, the frictionalforce between the clutch plates 16 a may be increased. That is, thecoupling force between the clutch plates 16 a may be increased. Thus,the clutch operation current to be supplied to the rotating shaft clutch16 may be increased.

Therefore, in the arithmetic processing part 51, first, the rotationalforce corresponding to each rotational speed N of the first rotatingshaft member 15 is obtained. Next, the friction force to be balancedwith the rotational force, that is, the coupling force between theclutch plates 16 a, is obtained. Further, the quantity of supply of theclutch operation current to obtain the coupling force is obtained. Anequation of the relation between the obtained rotational speed N andclutch operation current is then made. On the basis of the equation, theclutch driving part 42 increases the clutch operation current as therotational speed N increases, as shown in FIG. 12(d).

Next, an operation of the abnormal operation braking function will bedescribed.

(Abnormal Operation Braking Function)

As illustrated in FIG. 2, when the wind turbine generator is in normaloperation, the short-circuit relay 22 of the short-circuit brake 21 isenergized to be open. The alternating electric power from the dynamo 19is supplied to the rectifying section 32 of the bridge diode 33 and soon to charge the battery 4. On the other hand, when the controller 2 isbrought into an emergency stop because of an abnormal condition such aswear or damage of parts, all signal outputs being output to the windturbine generator main body 1 and so on are stopped. As a result,because energizing the short-circuit relay 22 of the short-circuit brake21 is stopped, the dynamo 19 is brought into a short-circuited state.

The above-described auxiliary power supply 16 c is connected to therotating shaft clutch 16. When the controller 2 is in an emergency stop,the deenergization operation type connection relay 16 d operates tosupply current from the auxiliary power supply 16 c to the coil member16 b. Thereby, the clutch plates 16 a are brought into a stronglycoupled state because the rotating shaft clutch 16 is an energisationoperation type. Thereby, the first rotating shaft member 15 and thesecond rotating shaft member 17 of the rotation support mechanism 14 isunited by the rotating shaft clutch 16. Thus, the rotational speed ofthe rotation support mechanism 14 is rapidly decreased due to the heavyload by the dynamo 19 in the short-circuited state.

As described above, the power supply unit of this embodiment comprises adriving force generation means (the wind turbine 11) for generatingdriving force by converting natural energy into kinetic energy, anelectric power generation means (the dynamo 19 for generating electricpower by being operated by the driving force, an energization operationtype clutch means (the rotating shaft clutch 16) for changing over withclutch force (coupling force) corresponding to operation current betweentransmission and interruption of the driving force from the drivingforce generation means to the electric power generation means, andclutch control means (the clutch driving part 42) for outputting theoperation current to the clutch means with controlling the operationcurrent to increase the clutch force in accordance with the drivingforce.

As described above, according to this embodiment, the clutch operationcurrent to be supplied to the rotating shaft clutch 16 is controlled inaccordance with the rotational speed of the first rotating shaft member15. Therefore, the consumption of the clutch operation current can bedecreased. In comparison with the case wherein a certain clutchoperation current continues to be supplied to the rotating shaft clutch16, the ratio of the electric power obtained by generation to the clutchoperation current used in the generation is improved. This realizeseffective electric power generation. That is, a large amount of electricpower can be obtained with low consumption.

In addition, according to this embodiment, because electric power isgenerated using wind power as a kind of natural energy, the generatorcan be disposed without particularly selecting the place. For example,in case of water power, the place is limited to the vicinity of a river.In addition, because the wind turbine 11 to be rotated by wind power isused, the structure can be simplified in comparison with a case ofgenerating with another structure.

In a modification of this embodiment, as shown in FIG. 12(e), the clutchoperation current may be increased stepwise. In this case, a translationtable is prepared in a non-illustrated memory area within the controller2. The table stores therein values of the relation between theabove-described rotational speed N and clutch operation current. At thistime, to a certain rotational speed N, the magnitude of the clutchoperation current is determined within a range wherein the clutch plates16 a can not slip on each other. Thereby, even when the rotational speedN increases in a certain range, a constant clutch operation current issupplied. Thus, the clutch operation current is increased stepwise. Inthis case, even when the rotational speed N increases in a certainrange, because a constant clutch operation current is supplied in thatrange, the consumption can be further decreased and the control issimplified.

Although the present invention has been described on the basis of apreferred embodiment, changes can be made within a scope not deviatingthe spirit of the present invention.

That is, in the embodiment, the clutch operation current is increasedcurvedly or stepwise. However, the present invention is not limited tothis. It suffices if the first and second rotating shaft members 15 and17 can rotate as one body. In addition, a large clutch operation currentis supplied upon start of an operation of the rotating shaft clutch 16to surely couple the first and second rotating shaft members 15 and 17.However, in order to further decrease the consumption of the clutchoperation current, the clutch operation current may be suppliedgradually from the start of the operation of the rotating shaft clutch16.

In addition, the program for realizing each function in theabove-described first and second embodiments may have been written in aROM of the memory unit in a read only manner. Otherwise, the programrecorded in a record medium such as a CD may be read out at need to bewritten in the memory unit. Further, the program transmitted through anelectrical communication line such as the Internet may be written in thememory unit.

Although the invention has been described in the above-preferredembodiments, the invention is never limited to those. It is to beunderstood that various embodiments not deviating from the spirit andscope of the invention can be made. Further, although operations andeffects of the constructions of the invention have been described in theembodiments, the operations and effects are by way of example and neverlimit the invention.

1. A power supply unit comprising: a storage means for storing electricpower that is used for operations of various devices; a charging meansfor transforming natural energy into an electrical energy, and chargingby supplying an electric power as the electric energy to said storagemeans; a charging changeover means for changing over between supply andstop of the electric power from said charging means to said storagemeans; and a charging changeover control means for controlling saidcharging changeover means such that supply and stop of said electricpower are repeated when a charging voltage for charging said storagemeans with electric power is not less than a predetermined value, andcontinues supply of said electric power when said charging voltage isless than the predetermined value.
 2. The power supply unit according toclaim 1, wherein said charging changeover control means obtains saidcharging voltage on the basis of the magnitude of said natural energy.3. A wind turbine generator comprising the power supply unit accordingto claim
 1. 4. A power supply unit comprising: a storage means forstoring electric power that is used for operations of various devices; acharging means for transforming natural energy into an electricalenergy, and charging by supplying an electric power as the electricenergy to said storage means; a charging changeover means for changingover between supply and stop of the electric power from said chargingmeans to said storage means; and a charging changeover control means forcontrolling said charging changeover means such that supply and stop ofsaid electric power is changed over at stop time intervals correspondingto a charging voltage for charging said storage means with electricpower.
 5. A power supply unit comprising: a storage means for storingelectric power that is used for operations of various devices; acharging means for transforming natural energy into an electricalenergy, and charging by supplying an electric power as the electricenergy to said storage means; a charging changeover means for changingover between supply and stop of the electric power from said chargingmeans to said storage means; and a charging changeover control means forcontrolling said charging changeover means such that supply and stop ofsaid electric power are repeated at stop time intervals corresponding toa charging voltage for charging said storage means with electric powerwhen said charging voltage is not less than a predetermined value, andcontinues supply of said electric power when said charging voltage isless than the predetermined value.
 6. A generator comprising: anelectric power generation means for generating electric power; a storagemeans for storing electric power generated by said electric powergeneration means; an output means for outputting electric power storedin said storage means to an external load or stopping the output; avoltage detection means for detecting a voltage of the electric powergenerated by said electric power generation means; and a control meansfor controlling said output means; said control means stops the outputof electric power to said external load when the voltage detected bysaid voltage detection means is not more than a predetermined value. 7.The generator according to claim 6, further including a stored electricpower detection means for detecting an amount of electric power storedin said storage means; and said control means stops the output ofelectric power to said external load when the voltage detected by saidvoltage detection means is not more than a predetermined value and theamount of electric power detected by said stored electric powerdetection means is not more than a predetermined value.
 8. The generatoraccording to claim 6, wherein said electric power generation meansgenerates electric power by converting kinetic energy for a rotatingshaft into electric power, and said voltage detection means detects thevoltage on the basis of the number of revolutions of said rotatingshaft.
 9. The generator according to claim 6, wherein a rotating shaftof said electric power generation means is rotated by wind power. 10.The generator according to claim 6, further including an inverter forconverting electric power stored in said storage means into electricpower having a specific wavelength and outputting the electric power tosaid external load, and said output means is included in said inverter.11. The generator according to claim 6, wherein said control means stopsthe output of the electric power to said external load after apredetermined time period elapses, when said control means stops theoutput.
 12. The generator according to claim 6, further including amemory means for storing operation contents of said control means, andsaid control means determines on the basis of the operation contentsstored in said memory means whether or not the output of the electricpower to said external load should be stopped when the voltage detectedby said voltage detection means is not more than the predeterminedvalue.
 13. The generator according to claim 12, further comprisingoperation means for rewriting memory contents of said memory means onthe basis of an operation of a user.
 14. The generator according toclaim 6, further comprising display means for displaying at least one ofthe number of revolutions of said shaft of said electric powergeneration means, electric power generated by said electric powergeneration means, the amount of electric power stored in said storagemeans, current of the electric power stored in said storage means,current of electric power consumed by said external load, and storagecontents stored in said memory means.
 15. A power supply unitcomprising: a storage means for storing electric power that is used foroperations of various devices; a charging means for transforming naturalenergy into an electrical energy, and charging said storage means withthe electric energy; an auxiliary charging means for charging saidstorage means with auxiliary electric power; and a charging controlmeans for monitoring a charging voltage of said storage means andpermitting that said auxiliary charging means charge auxiliary electricpower to said storage means when said charging voltage is less than apredetermined value.
 16. The power supply unit according to claim 15,wherein said auxiliary charging means comprises: an auxiliary powersupply means for outputting auxiliary electric power as direct currentof a predetermined voltage; and a changeover means for changing overbetween supply and stop of said auxiliary electric power to said storagemeans by said charging control means.
 17. A wind turbine generatorcomprising the power supply unit according to claim
 15. 18. A powersupply unit comprising: a storage means for storing electric power thatis used for operations of various devices; a charging means fortransforming natural energy into an electrical energy, and charging saidstorage means with the electric energy; an auxiliary charging means forcharging said storage means with auxiliary electric power such that saidstorage means has a charging voltage of not less than a predeterminedvalue.
 19. A wind turbine generator comprising the power supply unitaccording to claim
 18. 20. A power supply unit comprising: a drivingforce generation means for generating driving force by convertingnatural energy into kinetic energy; a measurement means for measuringthe magnitude of said driving force; an electric power generation meansfor generating electric power by being operated with the driving forceof said driving force generation means; a changeover means for changingover between transmission and interruption of the driving force of saiddriving force generation means to said electric power generation means;and a changeover control means for controlling said changeover meanssuch that the driving force from said driving force generation means tosaid electric power generation means is interrupted when the magnitudeof said driving force measured by said measurement means is less than apredetermined value, and the driving force is transmitted from saiddriving force generation means to said electric power generation meanswhen the magnitude of said driving force is not less than thepredetermined value.
 21. The power supply unit according to claim 20,wherein said changeover control means comprises a transmissioninhibition means for inhibiting the transmission of the driving forcefrom said driving force generation means to said electric powergeneration means till the magnitude of said driving force has increasedto not less than a transmission start value obtained by adding a certainvalue to said predetermined value when the magnitude of said drivingforce increases from less than said predetermined value to not less thansaid predetermined value.
 22. The power supply unit according to claim20, wherein said driving force generation means comprises: a rotationbody which rotates by said natural energy; and a rotating shaft whichrotates together with said rotation body.
 23. The power supply unitaccording to claim 20, wherein said measurement means measures therotational speed of said rotation body.
 24. The power supply unitaccording to claim 20, wherein said natural energy is wind power.
 25. Agenerator comprising the power supply unit according to claim
 20. 26. Apower supply unit comprising: a driving force generation means forgenerating driving force by converting natural energy into kineticenergy; an electric power generation means for generating electric powerby being operated with said driving force; a energisation operation typeclutch means for changing over with clutch force corresponding tooperation current between transmission and interruption of the drivingforce from said driving force generation means to said electric powergeneration means; and a clutch control means for outputting saidoperation current to said clutch means with controlling said operationcurrent such that said clutch force is increased in accordance with saiddriving force.
 27. The power supply unit according to claim 26, whereinsaid clutch control means outputs an operation current to generate alarge clutch force for operation start when said clutch means is changedover from an interruption state to a transmission state.
 28. The powersupply unit according to claim 26, wherein said clutch control meanscontrols said operation current such that said clutch force is increasedstepwise.
 29. The power supply unit according to claim 26, wherein saiddriving force generation means comprises: a rotation body which rotatesby said natural energy; and a rotating shaft which rotates together withsaid rotation body.
 30. The power supply unit according to claim 29,wherein said natural energy is wind power.
 31. A generator comprisingthe power supply unit according to claim 26.